Threaded inserts are a great way to be able to secure something to a wood base.
The problem is, the manufacturer specifically states that installing these inserts in to plywood is not recommended. Since plywood is layers of thin wood glued together, it does not have the same strength as solid wood. But if you have a plywood base, what can you do?
This instructable will show you how to install a threaded insert in to plywood but still have the strength of solid wood. Also note, that this is being done on a piece of scrap plywood for testing purposes only. I have an upcoming project where I expect to be installing about 15 or so of these inserts. The base wood is plywood, so I wanted to see if there was a way to get the strength of solid wood while still being able to use the more cost effective plywood.
Again, this is strictly for testing purposes and I am not sure if this is even the best solution for my\your needs. I'm looking forward to any comments that may improve on this.
Step 1: Drill and Install Insert in to Your Plywood Base.
I decided to test installing one of these inserts in to my plywood base. You can skip this step if you know you want to install the insert in to solid wood
A. Drill the appropriate hole for the insert you will be using.
B. Install the threaded insert
C. Test if insert is straight. Install a screw or bolt and see if it straight.
D. Test if screw and insert work to secure your item.
So it looks like this will work, but I'm concerned about long term. Over time, the device I secure with this insert may vibrate it loose and cause other issue. So let's see about getting the insert in to solid wood.
Step 2: Cut Out a Piece of Solid Wood
I cut a 2" piece from a 1"x2" piece of pine. For some reason I didn't take pictures of tracing the piece of wood around the space I wanted to install the insert, but the original hole is directly in the middle of the piece of wood. I chose to put tape around it so I could more easily see the border as I am routering it out.
Step 3: Router Out a Spot for the Wood.
Router out a spot big enogh to fit the piece of wood. Keep checking that the wood fits in to the routered space and that the depth is OK. If the solid wood is a little higher than the plywood, that is OK, it can be sanded down.
Step 4: Glue in to Place
Glue the solid wood in to the routered hole and let dry. Once you put the solid wood in, use some glue to help fill the gaps. Ultimately you will probably want to use actual wood filler to get a better look.
If you do plan on filling the gaps with wood filler and sanding everything smooth, do that now. You won't want to do it once to installed the threaded insert I will be painting the future project, so I would do that after sanding everything smooth.
Step 5: Drill Hole in to Solid Wood
Drill the correct size hole for your insert in to the solid wood and install the insert. You now have a threaded insert installed in to solid wood, but supporting your plywood base.
Step 6: Comparison
This last image is just a comparison of the threaded insert being installed in to the plywood and in to the solid wood.